The effects of lack (or severe restriction) of dietary protein on cholesterol esterification will be investigated (liver ACAT, serum LCAT and serum alpha lipoprotein). Casein and soy protein (which differ in levels of only a few essential amino acids) have different atherogenic and cholesteremic effects when fed to rabbits as components of a semipurified diet. The effect of specific amino acid supplementation of either protein on its atherogenicity will be studied. We propose to continue our studies on the influence of different types of dietary fiber on experimental atherosclerosis in rabbits and on cholesterol metabolism in rats. Specifically, the effects of alfalfa, lignin bran and wheat straw (among others) on cholesterol absorption, synthesis and degradation in rats will be assessed as will in vitro binding of bile acids and bile salts. The effects of these types of fiber on atherogenicity of semipurified, cholesterol-free diets will also be studied. We will also continue to study peanut oil -- native, cold-pressed and randomized for effects on cholesterol metabolism and atherosclerosis in rabbits and rats. BIBLIOGRAPHIC REFERENCES: D. Kritchevsky. Animal Models for Atherosclerosis Research. IN: Hypolipidemic Agents, ed. D. Kritchevsky, Springer-Verlag, Berlin 1975, pp. 216-227. D. Kritchevsky, S.A. Tepper and J.A. Story. Experimental atherosclerosis in rabbits fed cholesterol-free diets. 6. Skim Milk Powder. Nutrition Reports Int. 13:207-211 (1976).